Commit e3638151 authored May 04, 2018 by Dr. David Alan Gilbert Committed by Michael S. Tsirkin May 23, 2018

libvhost-user: Send messages with no data



The response to a VHOST_USER_POSTCOPY_ADVISE contains a fd but doesn't
actually contain any data.   FIx vu_message_write so that it doesn't
do a 0-byte write() call, since this was ending up with rc=0
that was confusing the error handling code.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

parent 9952e807

contrib/libvhost-user/libvhost-user.c

+9 −7

Original line number	Diff line number	Diff line
		@@ -323,6 +323,7 @@ vu_message_write(VuDev dev, int conn_fd, VhostUserMsg vmsg)
		rc = sendmsg(conn_fd, &msg, 0);
		} while (rc < 0 && (errno == EINTR \|\| errno == EAGAIN));

		if (vmsg->size) {
		do {
		if (vmsg->data) {
		rc = write(conn_fd, vmsg->data, vmsg->size);
		@@ -330,6 +331,7 @@ vu_message_write(VuDev dev, int conn_fd, VhostUserMsg vmsg)
		rc = write(conn_fd, p + VHOST_USER_HDR_SIZE, vmsg->size);
		}
		} while (rc < 0 && (errno == EINTR \|\| errno == EAGAIN));
		}

		if (rc <= 0) {
		vu_panic(dev, "Error while writing: %s", strerror(errno));